1. Field of the Invention
This invention relates to a knock-type writing instrument in which the writing extremity end is extended out of or retracted into the instrument through a knocking operation, and more particularly a knock-type writing instrument provided with a clip releasing mechanism for releasing said extended-out state when the clip is opened under a state in which the writing extremity end is extended out of the instrument.
2. Description of the Related Art
As this kind of knock-type writing instrument in the prior art, there has been provided, as already disclosed in the gazette of Japanese Patent Laid-Open No. Hei 10-264584, a writing instrument in which the outer peripheral surface of the rotor is axially provided with protrusions to be guided at the fixed cam slant surface of the inner surface of the barrel, and protruded engaging section formed at the front side of said protrusions and engaged with the concave engaged sections inside the ball at the extremity end of the clip.
This knock-type writing instrument is constituted such that an engaged state having said protruded engaging section at the outer peripheral surface of the rotor engaged with said concave engaging section of the clip is released to cause the extremity end of the writing instrument to be retracted by an opening operation of a clip when the writing instrument is put into the pocket in order to prevent the extremity end of the writing instrument from staining a cloth when the writing instrument is stored in a pocket of the cloth under a state in which the inner end of the writing instrument is being protruded by accident.
However, the aforesaid prior art knock-type writing instrument had a disadvantage that the axial length of the rotor is elongated due to the fact that the protrusion for use in guiding the fixed cam slant surface of the inner surface of the barrel and the protruded engaging section to be engaged with the concave engaged section inside the ball at the extremity end of the clip are separately arranged axially at the outer peripheral surface of the rotor. That is, since the axial space in the barrel was restricted by the rotor, this fact caused improvements of the writing instrument such as an increased ink volume in the writing instrument by extending the length of the refill or an arrangement of compact-sized writing instrument by shortening the length of the barrel and the like, for example, to be difficult.
In addition, in the case of the aforesaid prior art knock-type writing instrument, although the extremity end of the writing instrument was retracted into the barrel through the depressing operation at the knock part other than its practical use to protect by itself, there was a possibility that the writing extremity end was apt to be damaged when the writing instrument was dropped while the writing extremity end was being faced downward with the writing extremity end being exposed or when the writing was carried out with an excessive high writing pressure or when a load more than that required for writing operation directed toward the rear part of the barrel was applied to the writing extremity end. For example, in the case that the writing instrument was a ball-point pen, it was afraid that the extremity end edge of the tip was deformed, the ball was not rotated to cause the writing operation to become impossible or ink was flowed out between the ball and the extremity end.
The present invention has been invented in reference to the aforesaid circumstances and it is an object of the present invention to provide a knock-type writing instrument in which the cloth can be prevented from being stained with ink when the writing instrument is stored in a pocket and further the writing extremity end can be prevented from being damaged while it is being extended out of the barrel under an unintended state of use by a clip releasing mechanism having a compact structure.
The technical means of the present invention to resolve the aforesaid problems consists in a knock-type writing instrument having a clip releasing mechanism operated such that a knock rod arranged at the rear end of a barrel is knocked to enable a writing extremity end of a refill to be extended out of or retracted into an extremity end port of the barrel by a thrust lock mechanism provided with a rotor and a return spring, the rotor is engaged with a ball of a clip at the time of extended-out state and the engaged state of the rotor is released under an opening operation of said clip and this is characterized in that:
a window hole is opened at a peripheral surface of the barrel, the ball at the extremity end of the clip is provided with an inner protrusion which can be extended out of or retracted into said window hole;
the rotor is provided with a plurality of peripheral protrusions at its outer peripheral surface in a circumferential direction thereof to stop its rotation by being abutted against said inner protrusion of the clip when the writing extremity end is extended out of the barrel;
said thrust lock mechanism is provided with a fixed cam slant surface formed at the inner peripheral surface of the barrel, a thrust cam slant surface formed at the extremity end of the knock rod and axially slid in integral with said knock rod, a rotary cam slant surface formed at the rear end of the rotor, and a guiding slant surface formed at the surface of the writing extremity end at said inner protrusion;
said thrust lock mechanism causes the rotor to be rotated while said peripheral protrusion is guided by the fixed cam slant surface after said rotary cam slant surface is guided by the thrust cam slant surface when the knock operation for extending out the writing extremity end is carried out, one of said plurality of peripheral protrusions is abutted against said inner protrusion to cause the rotor to be stopped, and in turn when a knock operation for retracting the writing extremity end is carried out, one of said peripheral protrusions being abutted against the inner protrusion is guided by said guiding slant surface of the inner protrusion to cause the rotor to be rotated and said writing extremity end to be retracted after said rotary cam slant surface is guided by the thrust cam slant surface.
In accordance with the aforesaid technical means, the present invention has two functions, i.e. one function in which the peripheral protrusions of the rotor are guided by the fixed cam slant surface and the other function in which they are engaged with the ball at the extremity end of the clip. Then, when the writing extremity end is extended out of the barrel, a rotation of the rotor is stopped by abutting the peripheral protrusions at the outer peripheral surface against the inner protrusions of the clip. Accordingly, as the clip is opened, the inner protrusion of the clip is moved out of the barrel and is not abutted against the peripheral protrusions of the rotor, resulting in that the rotor is rotated to cause the writing extremity end to be retracted into the barrel.
In addition, in order to prevent the writing extremity end kept at its extended-out state from being damaged, there is provided a knock-type writing instrument having a clip releasing mechanism operated such that a knock rod arranged at the rear end of a barrel is knocked to enable a writing extremity end of a refill to be extended out of or retracted into an extremity end port of the barrel by a thrust lock mechanism provided with a rotor and a return spring, the rotor is engaged with a ball of a clip at the time of extended-out state and the engaged state of the rotor is released under an opening operation of said clip, wherein
a window hole is opened at a peripheral surface of the barrel, the ball at the extremity end of the clip is provided with an inner protrusion which can be extended out of or retracted into said window hole;
the rotor is provided with a plurality of peripheral protrusions at its outer peripheral surface to stop its rotation by being abutted against said inner protrusion of the clip when the writing extremity end is extended out of the barrel; and
the clip is constituted such that said inner protrusion is pushed up by said abutted peripheral protrusion when the writing extremity end at its protruded position is pushed in an axial rearward direction with a force of more than a predetermined load.
In this case, the aforesaid thrust lock mechanism is a mechanism constituted such that the extremity end of the knock rod and the rear end of the rotor, or the outer peripheral surface of the rotor and the inner peripheral surface of the barrel and the like are formed with cam slant surfaces to be engaged to each other, the rotor biased at the leading end side by a return spring is rotated under an engaging action of said cam slant surfaces, and the rotor is formed at a position where the writing extremity end of the refill installed at the extremity end of the rotor is extended out of the barrel extremity end port and another position where the writing extremity end is retracted from the barrel extremity end port.
In accordance with the aforesaid technical means, rotation of the rotor is prevented from being carried out by a method wherein the peripheral protrusions at the outer peripheral surface are abutted against the inner protrusions of the clip when the writing extremity end is extended out of the barrel. Accordingly, when the clip is opened, the inner protrusions of the clip are moved in an outward direction of the barrel and are not abutted against the peripheral protrusions of the rotor, resulting in that the rotor is rotated to cause the writing extremity end to be retracted into the barrel.
In addition, as the writing extremity end at the extended-out position is pushed rearwardly of the barrel with a force more than a predetermined load when the writing extremity end is extended out of the barrel, its pushing action becomes a rotating force for the rotor and the rotor is tried to rotate to push up the inner protrusions at the extremity end of the clip with the peripheral protrusions. Then, the clip is resiliently opened to cause the engaged state of the rotor to be released and the writing extremity end is retracted into the barrel.
Further, in order to attain a configuration of the clip in which said inner protrusions are pushed up with said peripheral protrusions being abutted when the writing extremity end at its extended-out position is pushed rearwardly of the barrel with a force more than a predetermined load, it is preferable that the abutted section between the aforesaid inner protrusion and the aforesaid peripheral protrusion is formed with a slant surface slidably contacted with the aforesaid peripheral protrusion and pushed up by it. In addition, it is satisfactory that said slant surface is of an R-shaped surface slidably contacted with the afore said peripheral protrusion and pushed up by it. Further, it does not show any problem to provide a configuration in which the inner protrusions are pushed up over the peripheral protrusions by making a proper setting of a tension force of the clip.
Further, preferably, the angle of said slant surfaces is set to be about 30xc2x0.